1. Field of the Invention
The present invention relates to a shift drive device in which a drum shifter turning around the same axis as that of a shift drum to turnably drive the shift drum is provided with a pin projecting therefrom and located offset from the turning axis. A shift arm includes one end that is secured to a shift spindle turnably secured by a transmission case. A guide hole is formed like an elongate hole lengthwise and extends in a radial direction of the shift spindle and is adapted to receive the pin inserted therethrough and engaged therewith. A turn-restriction hole is adapted to receive a restriction pin provided in the transmission case inserted therethrough. The pin is moved in the guide hole in response to the turn of the shift arm along with the shift spindle to turn the drum shifter and, to bring the restriction pin into abutment against a lateral edge of the turn-restriction hole, thereby restricting a turning range of the shift spindle and of the shift arm.
2. Description of Background Art
There is known a shift drive device in which a shift arm is secured to a shift spindle and is formed in a general L-shape to have a pair of arm portions extending from the shift spindle perpendicularly to each other. One of the arm portions is provided with a guide hole adapted to receive a pin of a drum shifter inserted thereinto and engaged therewith. The other arm portion is provided with a turn-restriction hole adapted to engage with a restriction pin of a transmission case to restrict the turning range of the shift spindle and of the shift arm. See, for example, Japanese Patent Laid-Open No. Hei 6-117533.
However, since the shift arm disclosed in Japanese Patent Laid-Open No. Hei 6-117533 is formed in a general L-shape, a space needed to turn the shift arm therein is increased to decrease the flexibility of the arrangement of other parts in the vicinity of the shift arm.